ARM: mvebu: Relocate Armada 370/XP DeviceBus device tree nodes

Now that mbus has been added to the device tree, it's possible to
move the DeviceBus out of internal registers, placing it directly
below the mbus. This is a more accurate representation of the hardware.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>